Number 215, February 24, 1995 by Phillip F. Schewe and Ben Stein|
CESIUM ATOMS HAVE BEEN COOLED TO 700 NANOKELVINS , the lowest 3D temperatures
ever achieved in an atom. Researchers at NIST (contact William Phillips
at 301- 975-6554) make special laser light patterns called "optical
lattices" which trap pre-cooled atoms at regular locations in the
pattern. Then, by gradually decreasing the intensity of the laser light,
they diminish interactions between light's electric field and the atom.
This causes each atom to occupy a larger region of space. In "expanding"
to their new volume, the atoms expend energy, making them colder. Such
supercold atoms may someday be employed to make more accurate atomic clocks
and atomic interferometers. (Physical Review Letters, 27 February 1995.)
CHAOTIC PULSATING STAR: Detailed observations of the star R Scuti show
that its fluctuating light emissions conform to the mathematical definition
of chaos (J. Robert Buchler et al., Physical Review Letters, 6 February
1995). According to Zoltan Kollath of the University of Florida, this is
the first strong evidence for chaotic emissions from a star. He and his
colleagues assembled data taken over 15 years by numerous astronomers.
They deduce from the star's light curve (emission as a function of time)
the notion that the complex pulsation variability might result from the
overlap of as few as two different vibrational modes in the star. (Science
News, 18 February 1995.)
THE DEVELOPMENT OF LIGHTER BATTERIES would please anyone who drives
an electric car or uses a laptop computer. Heretofore the battery type
with the best gravimetric energy density (stored energy per battery weight)
is one that uses a lithium cathode and a lithium compound anode. A new
lithium battery developed at Tokyo University uses a lithium metal anode
and a cathode consisting of a composite of two organic materials (dimercaptan
and polyanilene). At peak performance the organic-cathode battery had an
energy density of more than 600 Watt-hours per kg, compared to an equivalent
density of about 400 for the most sophisticated commercially available
lithium battery, one using a LiCoO2 cathode. The new battery retained 80-90%
of its original energy storage capacity even after 100 recharging cycles.
(N. Oyama et al., Nature, 16 February 1995.)
PHYSICAL REVIEW LETTERS (PRL) , the premier weekly physics journal, will
go online in July 1995. Besides getting the full text of all articles,
the user will have access (through an electronic hyperlink) to abstract
information on referenced articles dating back to 1983 and stored on the
SPIN (Searchable Physics Information Notices) data base. The online text
for any one issue would become available on the publication cover date.
Maria Lebron, Associate Publisher at The American Physical Society, expects
some subscribers might want to receive only the online version, but that
the print version of the journal would continue into the foreseeable future.
(For more information about PRL, journalists can contact Lebron at firstname.lastname@example.org;
APS members should contact the Membership department at email@example.com.)
Other physics journals which have gone (or will be going) online are Applied
Physics Letters (in January 1995), published by the American Institute
of Physics; Classical and Quantum Gravity, published by the Institute of
Physics (UK); and Astrophysical Journal Letters (scheduled for Sept. 1995),
published by the American Astronomical Society. (Physics World, February